body {
    background-image: url(imagenes/velero.jpg);
    background-size: 100vw 100vh;
    background-attachment: fixed;
    margin: 0;
}

form {
    width: 500px;
    margin: auto;
    background: rgba(0,0,0, 0.3);
    padding: 20px;
    box-sizing: border-box;
    margin-top: 40px;
    border-radius: 10px;
} 

h2 {
    color: #57F7F2;
    text-align: center;
    margin: 0;
    font-size: 30px;
    margin-bottom: 30px;
    
}

input, textarea {
    width: 100%;
    margin-bottom: 15px;
    padding: 7.5px;
    box-sizing: border-box;
    font-size: 15px;
    border-radius: 7px;
    border: none;
}

textarea {
    max-height: 250px;
    min-height: 100px;
    max-width: 100%;
}

#boton {
    background: #297D7A;
    padding: 15px;
    color: #57F7F2;
}

#boton:hover {
    cursor: pointer;
}

@media (max-width:520px) {
    form{
        width: 100%;
    }
}